More about
control statements
Chapter
5
Whats new in Chapter 5
The switch statement
Variations of the for loop
Example using a do..while loop
Using end-of-file indicators
Break and continue statements
Logical operators and(&&) and or(||) and negation(!)
Also
less often used Exclusive OR (^)
There are also a lot of examples of programs using the
control structures
Variations of for
loops
You can start
with a high number and decrement instead of increment
for (c = 10; c > 0; c--)
You dont have to
increment or decrement by one
for (c = 10; c > 0; c-=2)
Remember what the
three parts of a for loop stand for:
initialize, terminating condition, change control variable
Any expression that does this will compile
You can also
declare the type of
the loop variable inside the for statement
for (int c=1; c<=30; c++)
It is best not to use this style if the variable will
be used outside the loop
Nested loops
public
static void main(String[ ] args)
{ int outside, inside;
for (outside=0;
outside <5; outside++)
{ for (inside = 0; inside < 5; inside++)
{ System.out.print(inside + " ");
}
System.out.println();
}
}
Walk through this loop
Variations on nested loops
for (outside=0;
outside <5; outside++)
{ for (inside =
0; inside < outside; inside++)
System.out.print(inside
+ " ");
System.out.println();
}
Another variation
for (outside=0;
outside <5; outside++)
{ for (inside =
outside; inside < 5; inside++)
System.out.print(inside
+ " ");
System.out.println();
}
break and continue
The break statement
always
Terminates the current iteration immediately, then
Terminates the loop
The continue statement
always
Terminates the current iteration immediately, then
Proceeds to start the next iteration
Breaking out of the middle of a loop
You can put the condition in the middle of a loop,
then use the break keyword to exit the loop
Execution will then continue after the last statement
in the loop block
This is not considered the best programming practice
You can always write a loop so you do not need to
break out of the middle
Complex Boolean expressions
are connected by
logical operators
They return type boolean
(true or false)
How to use the logical operators
AND && both operands
must be true for the statement as a whole to be true
( (6>5) && (4==7)
) is false
OR
||
if either operands is true, the statement as a whole is
true
( (6>5) || (4==7)
) is true
NOT ! Negates the operand
!(6==6) is false
